1. Technical Field
The present invention generally relates to a semiconductor module, and more particularly, to the repair system of a semiconductor module for repairing a defect using electric fuses and a method of controlling the same.
2. Related Art
With a recent increase in the amount of processed video data in the fields, such as computers, mobile phones, and smart chip cards, a required capacity of memory is suddenly increasing. For example, in the computer field, video RAM for a graphic board requires a high capacity because the processing speed of a CPU becomes several hundreds of GHz. Furthermore, in the mobile phone field, color video data is processed because a display device becomes colorful and a high capacity of memory is required because the amount of personal communication data through wireless web service increases. In the mobile phone field and the smart chip card field, a module system of a high-capacity multi-chip form is required due to a limited mounting space.
In general, in a semiconductor memory, such as RAM, or a semiconductor integrated circuit in which a memory circuit is embedded, a yield is improved by repairing a defective bit included in a memory array using a redundancy circuit equipped with an address circuit for storing redundant memory columns, memory rows, and defective addresses.
In this redundancy circuit, when setting a defective address, a method of using a fuse that can be programmed by physical opening or breaking through a laser is commonly used. For example, there is a repair method of cutting a fuse using a laser, storing information on a defective address, comparing the defective address with an input address, and replacing the defective address with a redundant memory row or a redundant memory column according to a result of the comparison. The fuse must be cut before a memory chip is sealed in a package. For this reason, it is not easy to repair a defect generated after the memory chip is packaged.
For example, if a defect occurs during a mounting test after mounting chips in a module form, the chips must be extracted from the module, a defective position must be checked while decapsulating the extracted chips one by one, and a defect must be repaired using a laser. As described above, in order to detect, verify, and repair a defect in chips of a module form, a lot of time and costs must be consumed.